Galaxies
... megaparsecs of the Milky Way Galaxy. Rotation speed is a measure of a spiral galaxy’s total mass, so it is perhaps not surprising that this property should be related to luminosity. What is surprising, though, is how tight the correlation is. The Tully-Fisher relation, as it is now known (after its ...
... megaparsecs of the Milky Way Galaxy. Rotation speed is a measure of a spiral galaxy’s total mass, so it is perhaps not surprising that this property should be related to luminosity. What is surprising, though, is how tight the correlation is. The Tully-Fisher relation, as it is now known (after its ...
IXO as an observatory in the large telescopes era
... alternative SMBH formation and growth scenarios are possible. For example, they may form via direct, monolithic collapse of hot, dense gas clumps (Bromm & Loeb 2003; Begelman et al. 2006) or via “quasistars” (Begelman et al. 2008). It must also be borne in mind that luminous, optical QSOs, hosting a ...
... alternative SMBH formation and growth scenarios are possible. For example, they may form via direct, monolithic collapse of hot, dense gas clumps (Bromm & Loeb 2003; Begelman et al. 2006) or via “quasistars” (Begelman et al. 2008). It must also be borne in mind that luminous, optical QSOs, hosting a ...
Teil 2
... orbital motion, i.e., they appear centred at the central meridian during the respective quadrature phases, thus are not facing each other as would be the case for a hypothetical reflection effect. The leading hemispheres on both components appear with an effectively lower temperature than the traili ...
... orbital motion, i.e., they appear centred at the central meridian during the respective quadrature phases, thus are not facing each other as would be the case for a hypothetical reflection effect. The leading hemispheres on both components appear with an effectively lower temperature than the traili ...
A comparison of the s- and r-process element evolution in local
... been underestimated due to the fact that HFS was not used by Sbordone et al. (2007 – private communication). In that case, the adopted values should be seen in the plots as upper limits. Like LMC06a, we excluded some observed stars from the sample since they exhibit anomalous values for [Ba/H] or [E ...
... been underestimated due to the fact that HFS was not used by Sbordone et al. (2007 – private communication). In that case, the adopted values should be seen in the plots as upper limits. Like LMC06a, we excluded some observed stars from the sample since they exhibit anomalous values for [Ba/H] or [E ...
A CHANDRA X-RAY STUDY OF THE DENSE GLOBULAR CLUSTER TERZAN... C. O. Heinke, P. D. Edmonds, J. E. Grindlay, and...
... from the corrected position of EXO 1745248. A combination of this star and another star just above it (star B) was shown in the cleaned CMD of EGC01 (their Fig. 8) as one of only two stars that lie more than 3 to the blue from the distribution of stars in that color-magnitude diagram. Our attempt ...
... from the corrected position of EXO 1745248. A combination of this star and another star just above it (star B) was shown in the cleaned CMD of EGC01 (their Fig. 8) as one of only two stars that lie more than 3 to the blue from the distribution of stars in that color-magnitude diagram. Our attempt ...
X-ray Observations of Cosmic Accelerators Greg Madejski SLAC/KIPAC
... to orbital modulation seen in the optical * Example: black hole binary Cygnus X-1 (RXTE data from Zycki et al. 2008) ...
... to orbital modulation seen in the optical * Example: black hole binary Cygnus X-1 (RXTE data from Zycki et al. 2008) ...
Microlensing Events by Proxima Centauri in 2014 and 2016
... To refine the impact parameters and times of closest approach, we obtained Hubble Space Telescope (HST ) images of the field on 2012 October 1. Observations were taken with the UVIS channel of the Wide Field Camera 3 (WFC3) in the F475W, F555W, F606W, and F814W filters. Since the background stars ar ...
... To refine the impact parameters and times of closest approach, we obtained Hubble Space Telescope (HST ) images of the field on 2012 October 1. Observations were taken with the UVIS channel of the Wide Field Camera 3 (WFC3) in the F475W, F555W, F606W, and F814W filters. Since the background stars ar ...
SNEWS - University of Minnesota
... • Type II SNe energy from gravitational collapse of iron core (also type Ib, Ic) – Can’t fuse iron – When Chandrasekhar mass of iron accumulates, core goes from white dwarf conditions to neutron star conditions ...
... • Type II SNe energy from gravitational collapse of iron core (also type Ib, Ic) – Can’t fuse iron – When Chandrasekhar mass of iron accumulates, core goes from white dwarf conditions to neutron star conditions ...
GRB – The Afterglow
... in the jet collide with each other. When the jet hits the ISM, the afterglow is produced ...
... in the jet collide with each other. When the jet hits the ISM, the afterglow is produced ...
The chemical composition of TS 01, the most oxygen
... of a factor 2. Thus the extreme O deficiency of this object is confirmed. The abundances of S and Ar are less than 1/30 of solar. The abundance of He relative to H is 0.089 ± 0.009. Standard models of stellar evolution and nucleosynthesis cannot explain the abundance pattern observed in the nebula. ...
... of a factor 2. Thus the extreme O deficiency of this object is confirmed. The abundances of S and Ar are less than 1/30 of solar. The abundance of He relative to H is 0.089 ± 0.009. Standard models of stellar evolution and nucleosynthesis cannot explain the abundance pattern observed in the nebula. ...
Dust input from AGB stars in the Large Magellanic Cloud
... The Large Magellanic Cloud (LMC) is an ideal local laboratory to investigate dust input from stars at subsolar metallicities (ZLMC ' 0.3−0.5 Z , Russell & Dopita 1992) with evolutionary dust models. During recent years IR dust emission from stellar sources in the LMC has been extensively studied in ...
... The Large Magellanic Cloud (LMC) is an ideal local laboratory to investigate dust input from stars at subsolar metallicities (ZLMC ' 0.3−0.5 Z , Russell & Dopita 1992) with evolutionary dust models. During recent years IR dust emission from stellar sources in the LMC has been extensively studied in ...
ABSTRACT Stellar feedback, star formation and
... dependent potential or companion galaxy, we do not expect to excite a long-lasting grand design spiral. In Paper II, we found that the addition of photoelectric heating reduced the gravitational collapse of smaller clouds, slightly lowering the star formation rate and leading to a stronger filamenta ...
... dependent potential or companion galaxy, we do not expect to excite a long-lasting grand design spiral. In Paper II, we found that the addition of photoelectric heating reduced the gravitational collapse of smaller clouds, slightly lowering the star formation rate and leading to a stronger filamenta ...
Galaxies and Their Structure
... from the spectra of over 40 spiral galaxies (at his time people thought the ``spiral nebulae'' were inside the Milky Way). He found that over 90% of the spectra showed redshifts which meant that they were moving away from us. Edwin Hubble and Milton Humason found distances to the spiral nebulae. Whe ...
... from the spectra of over 40 spiral galaxies (at his time people thought the ``spiral nebulae'' were inside the Milky Way). He found that over 90% of the spectra showed redshifts which meant that they were moving away from us. Edwin Hubble and Milton Humason found distances to the spiral nebulae. Whe ...
Stellar evolution
Stellar evolution is the process by which a star changes during its lifetime. Depending on the mass of the star, this lifetime ranges from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are born from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star.Nuclear fusion powers a star for most of its life. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red giant phase. Stars with at least half the mass of the Sun can also begin to generate energy through the fusion of helium at their core, whereas more-massive stars can fuse heavier elements along a series of concentric shells. Once a star like the Sun has exhausted its nuclear fuel, its core collapses into a dense white dwarf and the outer layers are expelled as a planetary nebula. Stars with around ten or more times the mass of the Sun can explode in a supernova as their inert iron cores collapse into an extremely dense neutron star or black hole. Although the universe is not old enough for any of the smallest red dwarfs to have reached the end of their lives, stellar models suggest they will slowly become brighter and hotter before running out of hydrogen fuel and becoming low-mass white dwarfs.Stellar evolution is not studied by observing the life of a single star, as most stellar changes occur too slowly to be detected, even over many centuries. Instead, astrophysicists come to understand how stars evolve by observing numerous stars at various points in their lifetime, and by simulating stellar structure using computer models.In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z = 6.60. Such stars are likely to have existed in the very early universe (i.e., at high redshift), and may have started the production of chemical elements heavier than hydrogen that are needed for the later formation of planets and life as we know it.